Two questions:

The "computer" in my '87 D150 originally controlled the TC lockup. Is it possible to wire up a toggle switch to manually control lockup (similar to a 46RH/A518OD)?

Does anyone have any literature (wiring diagram) for this particular tranny? None of my diagrams show any wires to the tranny (I do not have the FSM for '87)

I will need to double check the colors, but the three wires to the trans are white, purple, and brown. Brown is the neutral safety switch (traced back to starter relay). The purple and white are currently not hooked up. I assume at least one of these wires controls TC lockup....

TIA

-S/6

It sounds like you found the 3 wires going to the neutral safety/back-up lamp switch. What ever their color, the center one is the neutral safety, the two outer wires are for the back up lamps.

This information will cost you ..... The white wire goes to fuse #13 which is powered by the ignition switch "run" circuit. The violet (with black tracer) goes to the back-up lamps. The Brown (with yellow tracer) goes to the starter relay as you already figured out.

The following information will cost you double .... The lock-up torque converter is powered by a fourth wire that should be in the same wire harness going to the transmission. However, The lock-up wire goes to its own connector on the transmission. It is located just above the rear flange of the transmission oil pan toward the left (drivers side) of the vehicle. Might be all covered with lots of oily dirt so you can no longer see it. The wire should be 14 gauge, Dark Blue color. Apply 12 volts to this wire to make the converter lock up. Remove power to unlock. Can you find the fourth wire now?

Now this is what I would recommend..... just leave the wire connected to the transmission. Go find the lock-up relay under the hood, its the next relay to rear of the starter relay near the left hood hinge. It has 4 wires going to it. 3 wires in one connector and the 4th wire is by it self. Just disconnect that single fourth wire, leave the other 3 connected. Now connect a wire between that single terminal on the lock-up relay and your new switch in the cab. Connect a second wire from the other terminal of your switch in the cab to ground. There is a ground junction under the dash between the radio and steering column with some empty spade lugs. You can use that. Now your new switch is working in place of the computer box. The computer actually just grounded that single terminal on the lock-up relay, now your new switch in the cab is doing that job.
If you do it this way you do not need to cut, splice, or modify any of the factory wiring and you can reconnect it at any time.

Additional information you may not want to know.... That lock-up relay has two surge supression diodes built into it. This is to dampen the voltage spike from the lock-up solenoid in the transmission and also the coil inside the relay. If you try to do a continuity test on that relay you may get goofy readings because of those diodes. If you connect 12volt power to the wrong terminal of that relay or if you connect certain terminals to reverse polarity you will cause a dead short through those diodes which makes the magic smoke leak out.

Why are you removing/disconnecting the computer? Please send it to me.
The computer allows the converter to lock up between 36 and 55 MPH depending on how much throttle you give it (seems to depend on engine manifold vacuum). When the converter is locked up, the computer will unlock it if you step on the throttle when you are between 36 and 55 MPH, it also unlocks under closed throttle deceleration (curb idle switch on carburetor) at any speed. I"ve also noted on my 87 truck that the converter will not lock up or unlocks if the manifold vacuum becomes very high. There are a LOT of neat and special things built into that computer to control the converter and the ignition timing of the engine. Things that can NOT be duplicated my mechanical means.

Have fun and don't forget to send me your computer!!

Unless there is a seperate single wire switch around the corner (adjacent to the back pan rail) your lockup is still hydraulically controlled. there is no wiring involved. I have the brown, purple and white plug that you are talking about right here in my computer desk, and the brown (middle) wire is, yes the neutral safety switck, but the purple and white are for your back up lights. Neither of these has anything at all to do with lockup.

Many thanks for the info.....printer is workin' away!

The computer has been more or less dead weight for a few years (MSD ignition). I gave up on it after I had spent what I felt was waaaay too much time trying to figure out why my timing wandered 6-7*.

Anyway, I removed the computer and reduced my wiring harness to less than 1/2 of its original diameter....and the slant has run better ever since. I needed this info for a temporary fix, as I am planning an upgrade to the 46RH when the adapter plates from AREngineering become available. The way things are looking I will have the 904 for another summer, and i want it to survive for at least one more year (110k original miles!)

Will it hurt anything to leave it as-is with no lockup (besides accelerated clutch wear?) will it function basically as a non-lockup 904 or will it burn itself up? (this is merely curiosity, I will wire up a switch)

Thanks again When I have things "done" (are projects ever really done?) I am more than willing to send you my computer Craig.

-S/6

I can not imagine any problems to leave the lock-up inoperative. Even if the computer was hooked up and working....... if you drive at less than 55 MPH with your foot in the throttle then the computer will never allow the converter to lock up all day long. One day when I had my truck loaded and pulling a heavy trailer I pulled the wire on the lock-up relay so I could gain a few extra engine RPM's at highway speed. You will generate some extra heat with the converter in action but this is the same as a normal non-lockup transmission.

Wandering timing........ can be caused by excess endplay in the distributor shaft, or the plastic distributor gear worn, or some people say timing chain can cause it too.

Craig-

Verified last night, there are indeed 4 wires coming from my tranny that all go into one connector; and the one I "missed" (forgot about would be more accurate ) is...surprise...blue

I know exactly what relay you describe.... I remember thing "WTF is this for" when I was cutting the fat from my wiring harness. Fortunately I kept everything I took off just in case something like this popped up. I just hope the wires are not one of the wires I pulled the pins out of the bulkhead connector (I pulled two, one was the temp gauge, the other I do not recall....) I haven't checked, but after reading your response I am pretty sure I do not currently have working reverse lights.

In regards to the wandering timing, I replaced the distributor (and gear) and the timing set and my timing would still wander between 2-3 ATDC and 2-3 BTDC at idle. Since the computer controlled timing I figure the comp was getting a bad signal from somewhere. After switching to a std elec dist and MSD ignition my timing is, and has been, rock solid, and that mysterious idle mis-fire is gone (these were my main two reasons for ditching the computer), not to mention fuel mileage is up. What I really like is the wiring diagram for my truck now looks more akin to diagrams for early 70's vehicles (I made my own diagram as I went, again, for just such an occasion)

Anyway, thanks again, and the computer is yours if you really want it. Let me know if you need the connectors as well. Many of the wires are no longer intact (What's left of the wiring harness) but I can cut them far enough from the connector to make a good splice, if needed.

-S/6

aa_dodge@yahoo.com

Sorry to drag this up,but I have a dumb question,

Whats the preferred style of toggle switch for this?

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Nick

1987 Dodge D-100(225/904) Daily Driver
1979 Dodge Ramcharger (318/727/NP208)(Under Construction)

anyone?

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Nick

1987 Dodge D-100(225/904) Daily Driver
1979 Dodge Ramcharger (318/727/NP208)(Under Construction)

Sorry, I did not see this post pop up. I would think any switch that suits your fancy will do the job, but i would stay away from the cheap $2 switches. Spend a few extra bucks on a higher quality one.

If it was the type of switch you were referring to, a single throw, double pole switch is what you need (I think that is the correct term. Two wire terminals, two switch positions, on, or off.)

-S/6

So it really doesn't matter what style switch? (rocker vs. toggle,etc. )

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Nick

1987 Dodge D-100(225/904) Daily Driver
1979 Dodge Ramcharger (318/727/NP208)(Under Construction)

Whatever you prefer. At one point I considered getting a floor shifter with a large enough handle to accomodate a small rocker switch placed next to my thumb, so switching the lockup on/off would be a relatively easy, no-reach operation (i.e no reaching to the dash).

-S/6

OK,one more dumb question,as I prepare to finally do the SCC bypass...

Once the switch is installed,how do I know if the lock-up is "on"? I've never really messed around with lock up transmissions,so I'm not real knowledgable about them.

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Nick

1987 Dodge D-100(225/904) Daily Driver
1979 Dodge Ramcharger (318/727/NP208)(Under Construction)

When the engine dies at a light because your forgot to switch the lockup off?

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Joshua

OOoooohhh, there's one in every crowd!!! Heck, I'm usually him - but Joshie beat me to the punch (line)...

But seriously, I would probably use a "double pole, single throw" switch. four terminals, two circuits on and off only. One for the lock-up and one for a small but bright L.E.D. somewhere I would notice it. And. yeah, spend eight or ten bucks for a good switch instaed of the junkers at the generic stores. (That is, unless you like changing out the switches in your cool new setup every week or three)

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'64 Dart GT convertible, 64 Dart 170 2-door post sedan in faded blue and rust (the Az Dart) & a sixty THREE Dart 170 2-door post sedan in faded blue and rust. (future project)
Early Dart Disorder (EDD) is real, and I've got it!

So let me get this straight,I'm going to have to flip the switch every time I come to a stop?

_________________
Nick

1987 Dodge D-100(225/904) Daily Driver
1979 Dodge Ramcharger (318/727/NP208)(Under Construction)